Gallup poll: Obama has 9-point lead over Romney in swing states

President Obama speaks during a campaign event at the Southern Maine Community… (Jewel Samad / AFP/Getty…)

A new Gallup poll shows that President Obama has opened up his largest lead over Mitt Romney to date, both nationally and among voters in a dozen key November battlegrounds.

Obama's 51% to 42% lead among registered voters in 12 "swing states" is his first over Romney in the USA Today/Gallup poll. Romney led in those states 48% to 46% in the previous survey in mid-February.

Driving that advantage is a significant gender gap. The two are statistically tied among men, with Romney's 48% to 47% lead within the margin of error. But among women, Obama has a 54% to 36% lead.

The poll's findings come after a period in which women's health issues, more specifically access to contraception through health insurance, became a major issue in the presidential campaign.

Among women voters in swing states, healthcare was the top issue respondents said would influence their vote for president, followed by gas prices and unemployment. Among men, the top issue was the deficit and national debt. Healthcare ranked third, and unemployment ranked fifth.

Romney acknowledged Sunday that he has "work to do" to get his message out to women during a campaign stop in Wisconsin.

"We have work to do, to make sure we take our message to the women of America, so they understand how we're going to get good jobs and we're going to have a bright economic future for them and for their kids. And make sure that these distortions that the Democrats throw in are clarified and the truth is heard," Romney said, according to Politico.

Obama was favored among women voters by a margin of 56% to 43% over John McCain in 2008, according to the national exit poll.

The 12 states identified as "swing states" in the USA Today/Gallup poll are Nevada, Colorado, New Mexico, Iowa, Wisconsin, Michigan, Ohio, Pennsylvania, New Hampshire, Virginia, North Carolina and Florida.

Among all registered voters nationwide, Obama's lead over Romney is 49% to 45%. In February, the two men were tied 47% to 47%. Obama leads 48% to 40% among registered voters who identified as independents.

The data showed a sharp decline in enthusiasm among Romney supporters. In January, 56% of Romney voters said they were extremely or very enthusiastic about voting, compared with 50% of Obama voters who said the same. Now, just 43% of Romney voters say they're enthusiastic about voting, compared with 46% of Obama voters who say so.

The national poll of 901 registered voters was conducted from March 25-26. The swing state poll was conducted from March 20-26 among 933 registered voters.